diff --git a/src/base/array_storage.rs b/src/base/array_storage.rs index 37019e6d..15405a6a 100644 --- a/src/base/array_storage.rs +++ b/src/base/array_storage.rs @@ -130,6 +130,12 @@ where { self.clone() } + + #[inline] + fn forget_elements(self) { + // No additional cleanup required. + std::mem::forget(self); + } } unsafe impl RawStorageMut, Const> diff --git a/src/base/default_allocator.rs b/src/base/default_allocator.rs index 97278b54..3b5d1281 100644 --- a/src/base/default_allocator.rs +++ b/src/base/default_allocator.rs @@ -15,7 +15,7 @@ use crate::base::array_storage::ArrayStorage; use crate::base::dimension::Dim; #[cfg(any(feature = "alloc", feature = "std"))] use crate::base::dimension::{DimName, Dyn}; -use crate::base::storage::{RawStorage, RawStorageMut}; +use crate::base::storage::{RawStorage, RawStorageMut, Storage}; #[cfg(any(feature = "std", feature = "alloc"))] use crate::base::vec_storage::VecStorage; use crate::base::Scalar; @@ -210,8 +210,8 @@ where // Safety: // - We don’t care about dropping elements because the caller is responsible for dropping things. - // - We forget `buf` so that we don’t drop the other elements. - std::mem::forget(buf); + // - We forget `buf` so that we don’t drop the other elements, but ensure the buffer itself is cleaned up. + buf.forget_elements(); res } @@ -241,8 +241,8 @@ where // Safety: // - We don’t care about dropping elements because the caller is responsible for dropping things. - // - We forget `buf` so that we don’t drop the other elements. - std::mem::forget(buf); + // - We forget `buf` so that we don’t drop the other elements, but ensure the buffer itself is cleaned up. + buf.forget_elements(); res } @@ -272,8 +272,8 @@ where // Safety: // - We don’t care about dropping elements because the caller is responsible for dropping things. - // - We forget `buf` so that we don’t drop the other elements. - std::mem::forget(buf); + // - We forget `buf` so that we don’t drop the other elements, but ensure the buffer itself is cleaned up. + buf.forget_elements(); res } diff --git a/src/base/matrix_view.rs b/src/base/matrix_view.rs index 47b2965a..68e5d978 100644 --- a/src/base/matrix_view.rs +++ b/src/base/matrix_view.rs @@ -229,6 +229,11 @@ macro_rules! storage_impl( let it = MatrixIter::new(self).cloned(); DefaultAllocator::allocate_from_iterator(nrows, ncols, it) } + + #[inline] + fn forget_elements(self) { + // No cleanup required. + } } )*} ); diff --git a/src/base/storage.rs b/src/base/storage.rs index 93dbfcd8..708a1440 100644 --- a/src/base/storage.rs +++ b/src/base/storage.rs @@ -149,6 +149,9 @@ pub unsafe trait Storage: RawStorage { fn clone_owned(&self) -> Owned where DefaultAllocator: Allocator; + + /// Drops the storage without calling the destructors on the contained elements. + fn forget_elements(self); } /// Trait implemented by matrix data storage that can provide a mutable access to its elements. diff --git a/src/base/vec_storage.rs b/src/base/vec_storage.rs index 72f84499..f0a0593f 100644 --- a/src/base/vec_storage.rs +++ b/src/base/vec_storage.rs @@ -281,6 +281,17 @@ where { self.clone() } + + #[inline] + fn forget_elements(mut self) { + // SAFETY: setting the length to zero is always sound, as it does not + // cause any memory to be deemed initialized. If the previous length was + // non-zero, it is equivalent to using mem::forget to leak each element. + // Then, when this function returns, self.data is dropped, freeing the + // allocated memory, but the elements are not dropped because they are + // now considered uninitialized. + unsafe { self.data.set_len(0) }; + } } unsafe impl RawStorage for VecStorage { @@ -332,6 +343,17 @@ where { self.clone() } + + #[inline] + fn forget_elements(mut self) { + // SAFETY: setting the length to zero is always sound, as it does not + // cause any memory to be deemed initialized. If the previous length was + // non-zero, it is equivalent to using mem::forget to leak each element. + // Then, when this function returns, self.data is dropped, freeing the + // allocated memory, but the elements are not dropped because they are + // now considered uninitialized. + unsafe { self.data.set_len(0) }; + } } /*